Control valve main seal retainer with an assembly and removal tool

ABSTRACT

A system for sealing a head end of a cylinder to prevent a material flow through the cylinder. An o-ring inside the cylinder surrounds a piston when the piston is in a closed position inside the cylinder to prevent material from leaking into the cylinder around the piston. The o-ring is held in position by a groove inside the cylinder wall proximate a head end of the cylinder. A retainer ring has a first end held in place by a step protruding from the cylinder wall and a second end extending into a second end of the o-ring. The retainer ring applies a force to the retainer-ring which holds the o-ring inside the groove. The o-ring also applies a force to the retainer ring holding the o-ring in place.

FIELD OF THE INVENTION

This invention relates to a valve having a retainer for an o-ring in acylinder for sealing the cylinder when a piston is in a closed positionin the cylinder. This invention also relates to a tool and method forinsertion and removal of the retainer and o-ring in the cylinder.

PROBLEM

It is common to use a control valve to control the flow of materialthrough a pipeline. One type of control valve has a cylinder that has aninlet at a head end of the cylinder and an outlet in a side wall of thecylinder. A piston slides through the cylinder to control the materialflow through the cylinder. The position of the piston is controlled by aspring and the flow of material through a control line. As the pressureof material on a nose of the piston overcomes the pressure of thematerial in the control line and the spring on the back side of thepiston, the piston moves upwards in the cylinder and allows material toflow through the cylinder. In a closed position, the pressure of thespring and flow through the control line on the back side of the pistonare greater than the pressure of the material on the nose of the piston.The piston is proximate the head of the cylinder in the closed positionwhich prevents material from flowing through the cylinder.

It is also common to use an o-ring to seal the cylinder when the pistonis in the closed position. As the piston moves into the closed position,the nose of the piston moves through the center of the o-ring. Theo-ring is trapped between the nose of the piston and the walls of thecylinder to seal the cylinder and prevent leakage of material past thepiston and into the cylinder. The o-ring is kept in place in thecylinder by being placed in a groove inside the cylinder wall.

It is a problem that the piston may pull the o-ring from the groove aspressure moves the piston from the closed position to an open position.When the o-ring is dislodged from the groove, the seal created by theo-ring may not be adequate and undesirable leakage of material into thecylinder may occur. There is a need in the art for a retainer to preventthe o-ring from becoming dislodged from the groove of the cylinder.

SOLUTION

The above and other problems are solved and an advance in the art isachieved by the provision of a retainer for an o-ring and a tool forinserting and removing the retainer. The retainer of the presentinvention is a metal ring that is pressed through the o-ring so that theouter walls of the retainer remain inside the o-ring and press againstthe o-ring to hold the o-ring inside the groove. A first advantage ofthe retainer is that the retainer securely holds the o-ring in place inthe cylinder. A second advantage of the retainer is that the retainercan be used in any condition and in any type of cylinder. Thiseliminates the need for different types of retainers in differentoperating conditions and in different types of cylinder. A thirdadvantage of the retainer is that the piston is designed to have one endthat is used to insert the retainer in the cylinder and a second endthat can be used to remove the retainer. This eliminates the need for aspecial tool for inserting or removing the retainer.

In accordance with this invention, there is a groove in the cylinderwall proximate the head end of the cylinder. The head end of thecylinder wall has a ledge extending out into an opening in the head endbelow the groove. A ledge extending out from a cylinder wall or alongthe circumference of a piston will hereinafter be referred to as a step.An o-ring is placed inside the groove. A retainer is a ring made ofmetal or other rigid material. The retainer ring has an outer diameterthat is approximately the diameter of the inside of the cylinder and aninner diameter that is less than an inside diameter of the step. Thewall of the retainer is of a height that allows the retainer wall toextend into the o-ring when the retainer is at rest on the step on thehead end of the cylinder.

The retainer is pressed into the cylinder and through the o-ring. Onesurface of the retainer is held in place by the step. A second surfaceof the retainer extends into the o-ring and retainer wall pressesagainst the o-ring to hold the o-ring in the groove. The o-ring, inturn, presses against the retainer wall holding the retainer in place.In a preferred embodiment, both the first and second ends of theretainer walls have lead chamfers or angled edges to prevent damage tothe o-ring during insertion and removal of the retainer.

Insertion and removal of the retainer can be completed using the pistonas a tool. Insertion is completed using a first end or nose of thepiston. The piston has a step around the diameter of the nose. Theretainer fits over the nose with one surface of the retainer resting onthe step. The piston pushes the retainer through the cylinder andthrough the o-ring until the other surface of the retainer comes to reston the step near the head end of the cylinder.

Insertion of the o-ring and retainer is completed in the followingmanner. First, the o-ring is inserted into the groove inside thecylinder wall. The retainer is then placed into the cylinder from afirst end of the cylinder opposite the head end of the cylinder. Theretainer is slid into the cylinder until a first surface of the retaineris at rest on a surface of the o-ring. The piston is then placed nosefirst into the cylinder. The piston is pushed downward until the step onthe nose contacts a second surface of the retainer. The retainer ispushed through the o-ring by the piston until the first surface of theretainer at rest on the step at the head end of the cylinder.

A back end of the piston is used to remove the retainer from thecylinder. The back end has a step with an outside diameter that issmaller than the inside diameter of the step at the head of the cylinderand that is larger than the diameter of the inside of the retainer.Removal of the retainer is performed in the following manner. First, thepiston is removed from the cylinder. The back end of the piston is theninserted into an inlet at the head of the cylinder. The step on the backend of the piston contacts the inside diameter of the retainer andallows the back end of the piston to apply force to the retainer. Theback end of the piston is then pushed upward through the cylinder. Aforce is exerted on the retainer that pushes the retainer through o-ringand through the cylinder.

DESCRIPTION OF THE DRAWINGS

The above and other features of this invention can be understood fromreading the below Detailed Description and the following drawings:

FIG. 1 illustrates a common control valve incorporating a retainer ofthe present invention;

FIG. 2 illustrates a cross sectional view of the common control valve;

FIG. 3 illustrated an exploded view of a piston assembly from a firstperspective;

FIG. 4 illustrates a cross sectional view of the piston assembly;

FIG. 5 illustrates a flow diagram of a process for inserting theretainer; and

FIG. 6 illustrates a flow diagram for removing the retainer.

DETAILED DESCRIPTION

FIG. 1 illustrates control valve 100 having a housing 110. Inlet flange101 and outlet flange 102 connect control valve 100 to a pipeline (notshown). Material flows into control valve 100 through inlet 103 andexits control valve 100 through outlet 104. Piston assembly housing 105forms a cylindrical cavity between inlet 103 and outlet 104. A pistonassembly (illustrated in FIG. 3) is contained inside piston assemblyhousing 105 and regulates the flow of material through control valve100.

Control inlet port 108 is an opening in housing 110 proximate inlet 103and diverts a material flow into a control pipeline (shown in FIG. 2).Control inlet port 108 is illustrated with a plug 118 threaded into xport 108. Control port 109 is an opening in a top side of pistonassembly housing 105 for diverting a control material flow to a secondend of a cylinder. Control outlet port 107 is an opening in housing 100proximate outlet 104 and returns a material flow from a control line(shown in FIG. 2) to outlet 104. Plug 117 is illustrated threaded insidecontrol outlet port 107.

FIG. 2 is a cross sectional view of control valve 100 connected tocontrol line 200. Control line 200 has a first end 201 connected tocontrol inlet port 108 for receiving material from the inlet of controlvalve 100. The material flows through control line 200 to a conduitconnected to control port 109. The material then flows though controlport 109 into a cylinder 220 of piston assembly 250. A control pilotvalve 202 is down stream of y port 109 in control line 200. Controlpilot valve 202 is a faucet assembly that can be adjusted to regulatethe flow of material through control line 200. A second end 205 ofcontrol line 200 is connected to control outlet port 107 to returnmaterial from control line 200 to the material flow out of outlet 104.

Piston assembly 250 is comprised of a cylinder 220 and piston 221.Piston 221 is slidably mounted inside cylinder 220. Cylinder 220 has ahead end 231 with an inlet opening 230 that is proximate the inlet 103for receiving a flow of material from inlet 103. Outlet opening 232 isin a side wall of cylinder 220 and allows material to flow throughcylinder 220 to outlet 104. Piston 221 slides inside cylinder 220 toregulate the material flow through cylinder 220. In a closed position,piston 221 is proximate head end 231 and prevents fluid from flowinginto cylinder 220. In an open position, piston 221 is proximate a secondend 234 of cylinder 220 and the flow path between inlet opening 230 andoutlet opening 232 is unobstructed. Piston 221 can be in a positionanywhere between the open and closed positions to partially obstruct theflow path and regulate the flow of material through cylinder 220.

Spring 222 has a first end fixedly attached to an upper inside wall ofcylinder 220 and a second end fixedly attached to a second end of piston221. Spring 222 is used to control the position of piston 221 insidecylinder 220. The position of piston 221 is controlled based upon abalanced pressure principle. A material flow from control port 109applies a pressure P2 to a second end of piston 221. The material flowfrom inlet 103 applies pressure P1 to a nose end of piston 221.

When pilot valve 202 is closed material cannot flow to control outletport 107. This causes pressure P2 on the second end of piston 221 to beequal to pressure P1 on the head end of piston 221. Pressure P2 exertedby the control flow and spring 222 biases piston 221 to the closedposition when pilot valve 202 is closed. When pilot valve 202 is openthe flow of material to control outlet port 107 reduces pressure P2 onthe second end of piston 221. The force applied by P1 overcomes theforce applied by P2 which causes piston 221 to move towards the openposition. Material is allowed to flow through cylinder 220. The morepilot valve 202 is opened the more P2 is reduced which in turn controlsthe position of piston 221 in cylinder 220.

When piston 221 is in the closed position, a seal is needed to preventmaterial from leaking around piston 221 and into cylinder 220. FIGS. 3and 4 illustrate the components of piston assembly 250 that are used toseal cylinder 220 when piston 221 is in the closed position. FIG. 3 isan exploded view of the components of piston assembly 250 used forsealing cylinder 220. FIG. 4 is a cross sectional view of cylinderassembly 250 with piston 221 in the closed position. FIGS. 3 and 4 willbe referred in the below description to better describe the relationshipof components in the piston assembly 250.

Piston assembly 250 has an o-ring 300 that fits inside cylinder 220 toseal cylinder 220 when piston 221 is in the closed position. O-ring 300is a circular piece of rubber or another resilient material formed in aring. The circumference of o-ring 300 is slightly greater than theinside circumference of cylinder 220. O-ring 300 fits into groove 400 onthe inside wall of cylinder 220 proximate the head end 231 of cylinder220. Groove 400 is at a level in cylinder 220 that allows nose 320 ofpiston 221 to fit securely against o-ring 300 when piston 221 is in theclosed position (as shown in FIG. 4).

In order to prevent o-ring 300 from being pulled out of groove 400 bypiston 221 as piston 221 slides into towards the open position, retainerring 310 is placed into cylinder 220. When inserted into cylinder 220,retainer ring 310 presses against o-ring 300 to prevent o-ring 300 frombeing pulled out of groove 400. Retainer ring 310 is a ring formed froma metal or other rigid material. Lead chamfers 312 and 313 are anglededges on retaining ring 310 allowing retaining ring 310 to slide intoand out of place without damage to o-ring 300. Step 401 proximateorifice 230 is provided to support a second side of retaining ring 310.

Step 401 biases retaining ring in a position where a first side ofretaining ring 310 is inside o-ring 300 and holding o-ring 300 insidegroove 400. This allows retaining ring 310 and o-ring 300 to pressagainst one another and to secure one another in place. The height ofwalls 311 of retainer ring 310 is determined by the height of groove400. The inside diameter of retaining ring 310 is less then the insidediameter of step 401 to facilitate removal of retaining ring 310.

In order to eliminate the need for a tool to place retaining ring 310inside cylinder 220, piston 221 is designed to be used in the insertionand removal process for retaining ring 310. Piston 221 has a nose 320with a protruding step 321 around nose 320. (Step 321 has an outsidediameter substantially equal to but greater than the inside diameter ofretaining ring 310. Nose 320 fits into retainer ring 310 with step 321contacting a first end of retaining ring 310 to be used in the insertionprocess described below.) A second end 325 of piston 221 has aprotruding step 326 that has an outer circumference that is greater thaninside circumference of retaining ring 310 and less than the outercircumference of step 401. Second end 325 of piston 221 can fit intohead inlet opening 230 of cylinder 220 and can be used in the removalprocess described below.

FIG. 5 is a flow chart of a process 500 for inserting o-ring 300 andretainer ring 310 into cylinder 220 using piston 221 as an insertiontool. Process 500 begins in step 501 by inserting o-ring 300 into groove400 of cylinder 220. In step 502, retainer ring 310 is inserted intocylinder 220 from the second side 234. Retaining ring 310 is then restedso that a first end of retaining ring 310 is resting evenly on o-ring300 in step 503.

In step 504, piston 221 is inserted into a second end 234 of cylinder220 directly with nose 320 directly over retaining ring 310. Nose 320passes through retaining ring 310 until step 321 is in contact with asecond surface of retaining ring 310 in step 505. Piston 221 is thenpushed into cylinder 220 applying a force to retaining ring 310 in step506. Lead chamfer 312 guides retaining ring 310 over an inner surface ofo-ring 300. Process 500 ends in step 507 with retaining ring 310 beingpushed through o-ring 300 until a first surface of retaining ring 310contacts step 401.

FIG. 6 illustrates a removal process 600 for removing retaining ring 310using a second end of piston 221. Process 600 begins in step 601 byremoving piston 221 from cylinder 220. In step 602, a second end ofpiston 221 is inserted into orifice 230 of cylinder 220. Step 326 ofpiston 221 contacts a first surface of retainer ring 310 in step 603. Aforce is applied to retaining ring 310 by pushing piston 221 intocylinder 220 in step 604. In step 605, retaining ring 310 passes througho-ring 300 guided by lead chamfer 313. Process 600 ends in step 606 byremoving retaining ring 310 from cylinder 220 through an opening in thesecond side 234 of cylinder 220.

The above described is one possible exemplary embodiment of a main valveseal retainer and tool for use in inserting and removing the retainer.It is possible that one skilled in the art can and will designalternative retainers and tools that infringe on this invention asclaimed below either literally or through the Doctrine of Equivalents.

What is claimed is:
 1. A system for sealing a head end of a cylindercomprising:a piston slidably mounted inside said cylinder; an o-ring forsealing said cylinder when said piston is in a closed position; a groovein an inside wall of said cylinder proximate said head end of saidcylinder for receiving said o-ring; retainer means protruding into saido-ring inside said groove for applying a force to said o-ring to preventsaid o-ring from being forced out of said groove; and means in saidcylinder for preventing movement of said retainer means.
 2. The systemof claim 1 further comprising:chamfer means on a first end of saidretainer means for preventing damage to said o-ring during insertion ofsaid retainer means into said cylinder.
 3. The system of claim 1 furthercomprising:chamfer means on a second end of said retainer means forpreventing damage to said o-ring during removal of said retainer meansfrom said cylinder.
 4. The system of claim 1 wherein said means forpreventing movement comprises:a step protruding from the circumferenceof said inside wall of said cylinder between said groove and said headend.
 5. The system of claim 1 further comprising:means on a first end ofsaid piston for inserting said retainer means into said cylinder.
 6. Thesystem of claim 5 wherein said means for inserting on said first end ofsaid piston is a step protruding from a nose end of said piston.
 7. Thesystem of claim 1 wherein said means for removing is a step protrudingfrom the circumference of said second end of said piston.
 8. The systemof claim 1 wherein said retainer means is a retaining ring made fromrigid material.